Light-filtering overcoating containing diphenylene oxide



any means complete. amount of these constituents present in the lac- Patented June 9, 1936 LIGHT-FILTERING OVERCOA TING CON- TAINING DIPHENYLENE OXIDE Thomas F. Murray, Jr., Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York \No Drawing. Application January 16, 1932,

Serial No. 587,163

10 Claims.

This invention relates to protective coatings and to articles coated therewith.- One of its objects is to provide a filter for the absorption of ultra-violet light. Another object is to provide a lacquer or overcoating which absorbs substantially all the ultra-violet light which .would have a deleterious efiect upon the underlying surface. Another object is to provide a cellulose acetate lacquer which, having been applied over a nitrocellulose lacquer, absorbs many of the light rays which have a decomposing effect upon nitrocellulose.

It is a well known fact that nitrocellulose lacquers lose their gloss with relatively great rapidity when exposed to the elements. The de-lustering and decomposition of nitrocellulose lacquer surfaces, while to some extent due to inclement weather conditions, is primarily due to the ultraviolet rays from the sun, which penetrate and decompose the surface layer.

While the addition of pigments and plasticizers to nitrocellulose compositions aids to a slight extent in rendering a nitrocellulose layer used as an outer coating less afiected by the ultraviolet light, the protection they afiord is not by Even with a considerable been found that under such conditions the exposed cellulose nitrate will be decomposed by the ultraviolet light falling upon its surface.

It has previously been proposed to protect cellulose nitrate lacquers from ultra-violet light by overcoating them with cellulose acetate lacquers.

' Cellulose acetate of itself does not decompose appreciably under the influence of ultra-violet light. However, it will not fully protect an under layer of cellulose nitrate over which it may be coated, for the reason that it does not completely absorb those light rays which decompose the nitrate.

the passage of ultra-violet light. Diphenylene oxide has the formula:

and is otherwise known as dibenzofurane. Its

preparation has been described in the literature. It shows a high degree of stability in ultraviolet light, and when added to a cellulose acetate lacquer in amounts of from approximately 0.25% to 5% or more based on the Weight of the cellulose acetate, it effectively protects from ultraviolet light a nitrocellulose or other surface overcoated with the cellulose acetate lacquer.

It is not particularly material what type of vehicle holds the filter, as suitable varnishes, gums, Waxes, shellacs, etc. are for some purposes as useful as cellulose acetate as vehicles in which to incorporate the diphenylene oxide. Nor should I be understood to restrict myself to cellulose acetate specifically as a cellulose derivative vehicle for a light-filtering overcoating. There are numerous other esters of cellulose, such as cellulose propionate, cellulose butyrate, cellulose acetate-propionate, cellulose acetate-benzoate, cellulose nitro-acetate, cellulose phospho-acetate, etc., many of which are useful as vehicles in which to incorporate the. filter for use as an overcoating. In selecting the vehicle it must, of course, be borne in mind that only those substances are suitable which are themselves not as rapidly decomposed as the subcoating which they are used to protect.

My novel overcoating lacquer may be prepared in the following manner, although any method which uniformly disperses the diphenylene oxide throughout the vehicle used may generally be employed. Cellulose acetate, for example, may be mixed with approximately 3% of its weight of diphenylene oxide, with or without the addition of say up to 50% of a suitable plasticizer. This mixture may then be dissolved in a suitable solvent or solvent mixture, such as one made up of 15% ethyl acetate, 50% acetone, 20% ethyl lactate and 15% denatured alcohol, approximately one gallon of this solvent being required for 20 ounces of cellulose acetate. This example is given merely to acquaint those skilled in the art with one manner of incorporating the filter, and I am not to be limited by the details or proportions of this example except as may be indicated by the appended claims.

The term overcoating, and the description of these over-coatings in connection with lacquers are to be understood broadly rather than specifically, as it will be apparent that the value of my invention lies in the fact that by interposing, between the cellulose nitrate layer and the source of the ultra-violet rays, a vehicle containing the ultra-violet light filter, the nitrate underlayer will be protected from decomposition and deterioration. Thus, the cellulose acetate overcoating may consist of an already formed sheet containing the filter, which sheet is interposed between the cellulose nitrate sheet to be protected and the source of the ultra-violet light. Furthermore, in the case of laminated glass, for instance, the cellulose derii ative reinforcement interposed between the glass laminations may consist of a cellulose nitrate interlayer' on either side of which is coated, or otherwise imposed, a layer or coating of a vehicle such as cellulose acetate with which has been incorporated an ultra-violet light filter. Thus, even though the cellulose nitrate interlayer be covered on both sides with glass, it is first covered with a vehicle containing an ultra-violet light filter, so that the cellulose nitrate is protected f from decomposition by the ultra-violet light which would otherwise penetrate the cellulose nitrate and decompose it. Thus, the term overcoating or light filtering coating used in this specification and the appended claims is not to be confined to a mere lacquer top coat, but is to be construed broadly as any shielding layer containing an ultra-violet filter for preventing decomposition of cellulose nitrate by ultra-violet light, or for protecting any surface or substance from ultra-violet light. 7

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. "An article of manufacture'having a closely I adhering lacquer coating decomposable by sunlight, and a light filtering over-coating comprising an organic derivative of celluloseand diphenylene oxide.

2. An article of manufacture having a closely adhering lacquer coating decomposable by sunlight, and a light filtering over-coating comprislng cellulose acetate and diphenylene oxide.

3; An article of manufacture having a closely adhering lacquer coating decomposable by sunlight, and a light filtering over-coating which comprises cellulose acetate, diphenylene oxide and aplasticizer. I I

4. An article of manufacture having a light filtering protective covering comprising a cellulose acetate overcoating superimposed upon a cellulose nitrate coating, the overcoating, due to its content of diphenylene oxide, having the characteristic that it absorbs'subst'antially all the ultra-violet that reaches the earth's surface from the sun, and thereby protects the cellulose nitrate coating from decomposition.

5. An article of manufacture having a cellulose nitrate coating with an overcoating of celparts of cellulose acetate and from 0.25 part to 5 parts, by weight, of'diphen'ylene oxide.

10. A composition of matter comprising 100 parts of a cellulose organic ester and from 0.25

THOMAS F. MURRAY, JR.

- part to 5 parts, by weight, of diphenylene oxide. 

